CN217238275U

CN217238275U - Partial discharge ultrasonic signal conditioning device suitable for multi-application scene

Info

Publication number: CN217238275U
Application number: CN202220685946.6U
Authority: CN
Inventors: 何平; 金春雷; 赵彤
Original assignee: BAODING TIANWEI XINYU TECHNOLOGY DEVELOPMENT CO LTD
Current assignee: BAODING TIANWEI XINYU TECHNOLOGY DEVELOPMENT CO LTD
Priority date: 2022-03-28
Filing date: 2022-03-28
Publication date: 2022-08-19
Anticipated expiration: 2032-03-28

Abstract

The utility model relates to a partial discharge ultrasonic signal conditioning device of multi-application scene, its characterized in that: comprises an input frequency selection protection unit (1), a PGA unit (2), a program control frequency selection unit (3) and an acquisition driving unit (4) which are sequentially transmitted by signals; the input frequency-selecting protection unit (1) comprises a high-pass RC filter with the characteristic of 10KHz and a low-capacitive protection circuit which can limit the amplitude of an input signal to be 0.3V higher than a positive power supply rail and 0.3V lower than a negative power supply rail; the input frequency-selecting protection unit (1) is electrically connected with the PGA unit (2); the PGA unit (2) is provided with an amplifier LNA of which the input end is electrically connected with the output end of the input frequency selection protection unit (1) and an amplifier PGA of which the input end is electrically connected with the output end of the amplifier LNA; the utility model relates to a rationally, compact structure and convenient to use.

Description

Partial discharge ultrasonic signal conditioning device suitable for multi-application scene

Technical Field

The utility model relates to a high-voltage electrical equipment partial discharge detects technical field, specific theory relates to a partial discharge ultrasonic signal conditioning device suitable for multi-application scene.

Background

The ultrasonic detection technology, as a main means of partial discharge detection, has the advantages of being free from power interference, capable of accurately measuring a discharge position and the like. Ultrasound can propagate in solids, liquids and gases. In a power system, the application scenes of ultrasonic waves in air transmission are high-voltage overhead lines, switch cabinets, power cables, dry-type transformers and the like, the scenes of ultrasonic waves in high-stability gas transmission are mainly GIS, and the scenes of ultrasonic waves in liquid transmission are mainly oil-immersed transformers. The frequency of an ultrasonic signal propagated in the air is generally 20-60KHz, and the attenuation is large; the frequency of the ultrasonic signal transmitted in SF6 gas is 20-80 KHz; the frequency of the ultrasonic signal propagating in the transformer oil is typically 80-200 KHz. For the different application scenarios described above, different types of ultrasonic sensors need to be used. The present ultrasonic signal conditioning method is generally designed only for one application scene, and the utility model discloses the scheme is a method that is applicable to the ultrasonic signal conditioning of above-mentioned multiple application scene. Due to the fact that the propagation speeds and the attenuation rates of the ultrasonic waves in different media are different, the presented frequency characteristics are different. The utility model discloses a for solving above-mentioned problem, this device is become the flexible variable of gain with signal conditioning process design, and the multifrequency section is optional, gathers the fixed just degradable frequency of drive division gain.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems, the utility model adopts the following technical proposal:

a partial discharge ultrasonic signal conditioning device suitable for multiple application scenes comprises an input frequency selection protection unit, a PGA unit, a program control frequency selection unit and an acquisition driving unit which are sequentially transmitted by signals;

the input frequency-selecting protection unit comprises a high-pass RC filter with the characteristic of 10KHz and a low-capacitive protection circuit which can limit the amplitude of an input signal to be 0.3V higher than a positive power supply rail and 0.3V lower than a negative power supply rail; the input frequency-selecting protection unit is electrically connected with the PGA unit;

the PGA unit is provided with an amplifier LNA of which the input end is electrically connected with the output end of the input frequency selection protection unit and an amplifier PGA of which the input end is electrically connected with the output end of the amplifier LNA;

the program control frequency selection unit comprises an analog switch and a plurality of analog filtering frequency selection units;

the acquisition driving unit comprises a frequency reduction amplifier and has the functions of 20dB gain amplification and frequency reduction.

The amplifier PGA comprises an amplifier and a program-controlled precise resistance network; the program-controlled precise resistance network comprises an analog switch with the on-resistance smaller than 1 omega and a plurality of high-stability precise resistors.

The input frequency selection protection unit comprises diodes D1, D2, D3 and D4, capacitors C1 and C2, and resistors R1 and R2;

diodes D1, D2, D3 and D4 form a differential amplitude limiting protection circuit, and corresponding input signals are V +, V-and V-; the input end formed by the capacitor C1, the resistor R1, the capacitor C2 and the resistor R2 is electrically connected with the output end of the differential amplitude limiting protection circuit; the diodes D1 and D3 are connected with the output end of the resistor R1 through a capacitor C1, the diodes D2 and D4 are connected with the output end of the resistor R2 through a capacitor C2, and the other ends of the resistors R1 and R2 are respectively grounded;

the amplifier LNA comprises a chip U1, and the amplifier PGA comprises a chip U2, resistors R3, R4, R5 and R6;

a pin 4 and a pin 5 of a chip U1 are directly connected to the output end of the differential high-pass RC filter respectively; the pin 15 is connected into

pins

3, 14, 11 and 6 of the chip U2 through resistors R3, R4, R5 and R6 respectively; a pin 2 of the chip U1 is connected to a corresponding terminal pin of the chip U2;

the program control frequency selection unit comprises a chip U3, capacitors C4, C5, C6, C7, C8 and C9, inductors L1, L2 and L3; the pin 11 of the chip U1 is connected with the corresponding pin of the chip U3 through a coupling capacitor C3;

capacitors C4, C7 and inductor L1, capacitors C5, C8 and inductor L2, and capacitors C6, C9 and inductor L3 respectively form a first filter circuit, a second filter circuit and a third filter circuit;

the

output pins

3, 14 and 11 of the chip U3 are respectively connected with the corresponding first, second and third filter circuits; the acquisition driving unit comprises a chip U4, resistors R7, R8 and R9, and capacitors C10 and C11; the output ends of the first filter circuit, the second filter circuit and the third filter circuit are connected with one end of a resistor R7, the other end of the resistor R7 is divided into two paths, one path is grounded through a resistor R8, the other path is connected to a pin 2 of a U4 of a chip through a capacitor C10, and a capacitor C11 and a resistor R9 are connected between the pin 2 and a pin 6 in parallel.

The ultrasonic signal is transmitted in the air, and the main application scene is the live detection of high-voltage overhead lines, switch cabinets, power cables and dry-type transformers. The ultrasonic signal has very serious amplitude attenuation under the application scene, and the frequency is generally between 20 and 60 KHz. The ultrasonic wave is transmitted in SF6 gas medium, and the main application scene is a closed high-pressure gas charging switch. The frequency of the ultrasonic wave in this scene is generally 20-80 KHz. Ultrasonic signals are transmitted in a liquid medium, an oil-filled power transformer is a main application scene, and the frequency of the ultrasonic waves is generally 80-200KHz in the application scene.

Since the above application scenarios generally involve complicated electromagnetic environments, the higher voltage signal may be coupled to the input stage in a variety of ways. Once the input stage signal is much higher than the positive supply rail voltage or much lower than the negative supply rail voltage, permanent damage to the signal conditioning circuitry can result. Low-frequency vibration signals generated when large-scale power equipment operates are also introduced into the input stage as one of interference sources.

Drawings

Fig. 1 is a circuit block diagram of the present invention.

Fig. 2 is a circuit diagram of the present invention.

Wherein: the device comprises an input frequency selection protection unit (1), a PGA unit (2), a program control frequency selection unit (3) and an acquisition driving unit (4).

Detailed Description

As shown in fig. 1-2, the present invention relates to a partial discharge ultrasonic signal conditioning device suitable for multiple application scenarios, which comprises an input frequency-selecting protection unit 1, a PGA unit 2, a program-controlled frequency-selecting unit 3 and an acquisition driving unit 4, which are sequentially signal-transmitted;

the input frequency-selecting protection unit 1 comprises a high-pass RC filter with the characteristic of 10KHz and a low-capacitive protection circuit which can limit the amplitude of an input signal to be 0.3V higher than a positive power supply rail and 0.3V lower than a negative power supply rail; the input frequency-selecting protection unit 1 and the PGA unit 2 are coupled through a capacitive unit.

Low-frequency interference signals introduced by the input stage are filtered, and meanwhile, the amplitude of the input signals is limited to a range set near a power supply voltage rail.

Conventional overvoltage protection devices generally have a large capacitance value, and the large capacitance value can cause effective signals to be lost, so it is important that the input limiting circuit has a low equivalent capacitance characteristic.

A PGA unit 2 having an amplifier LNA with an input terminal electrically connected to the output terminal of the input frequency-selecting protection unit 1 and an amplifier PGA with an input terminal electrically connected to the output terminal of the amplifier LNA; the amplifier PGA comprises an amplifier with balanced input gain set by a single resistor and a program-controlled precise resistor network; the program-controlled precise resistance network comprises an analog switch with the on-resistance smaller than 1 omega and a plurality of high-stability precise resistors.

The amplifier LNA is responsible for converting the impedance of the high-impedance ultrasonic sensor into a low-impedance low-noise voltage source, which becomes the low-impedance, low-noise signal source of the post-amplifier PGA. Because the ultrasonic wave sensing is attenuated differently in different media, in order to enable the signal to become a voltage signal which can be identified by a rear-stage ADC, different gain values are set by PGA modules in the PGA unit according to different scenes;

the frequency characteristics of the partial discharge ultrasonic signals in different media are different, and the signal-to-noise ratio of the signal conditioning unit can be adjusted to the optimal state by using the frequency selection unit matched with the signals. The PGA gain is set to the highest gain as a characteristic of the ultrasonic wave propagating in the gas.

The program control frequency selection unit 3 is composed of an analog switch with the on-resistance smaller than 1 omega and a plurality of analog filtering frequency selection units. The analog switch with the on-resistance smaller than 1 omega is used for combining the plurality of analog filtering frequency selection units;

and accessing information of the PGA gain, and adjusting the frequency band to a frequency band according with a corresponding application scene. The bandwidth is as low as possible to reduce the gain noise introduced by too high gain, and the ultrasonic wave reduces the PGA gain according to the characteristics of the ultrasonic wave in the application scenes of the gas reinforced body and the liquid reinforced body, so that the gain noise can be effectively reduced, and the frequency band of the program control frequency selection unit is adjusted to the frequency band of the corresponding scene to further reduce the noise level.

The acquisition driving unit 4 comprises a down-conversion amplifier with a fixed gain of 20dB, and has the functions of gain amplification of 20dB and frequency conversion. The acquisition driving unit amplifies the signals subjected to frequency selection by the frequency selection unit by 20 dB; then, the high frequency component is removed by the frequency converter to keep the amplitude characteristic of the signal, so as to ensure that the low sampling rate ADC can also identify the partial discharge ultrasonic signal.

The amplifier LNA mainly transforms the ultrasonic sensor impedance to make it a low impedance signal source. The low impedance signal source is more easily matched to the post-amplifier PGA. The low input resistance of the PGA can effectively reduce the thermal noise of the resistor.

In fig. 2, the input frequency-selective protection unit 1 includes diodes D1, D2, D3, D4, capacitors C1, C2 and resistors R1, R2;

pins

the program-controlled frequency selection unit 3 comprises a chip U3, capacitors C4, C5, C6, C7, C8 and C9, and inductors L1, L2 and L3; the pin 11 of the chip U1 is connected with the corresponding pin of the chip U3 through a coupling capacitor C3;

capacitors C4, C7, an inductor L1, capacitors C5, C8, an inductor L2, capacitors C6, C9 and the inductor L3 respectively form a first filter circuit, a second filter circuit and a third filter circuit;

the

output pins

3, 14 and 11 of the chip U3 are respectively connected with the corresponding first, second and third filter circuits;

the acquisition driving unit 4 comprises a chip U4, resistors R7, R8 and R9, and capacitors C10 and C11;

the output ends of the first filter circuit, the second filter circuit and the third filter circuit are connected with one end of a resistor R7, the other end of the resistor R7 is divided into two paths, one path is grounded through a resistor R8, the other path is connected to a pin 2 of a U4 of a chip through a capacitor C10, and a capacitor C11 and a resistor R9 are connected between the pin 2 and a pin 6 in parallel.

The utility model discloses mainly obtain extensive application in the multi-scene supersound partial discharge of electric power industry detects.

The present invention has been fully described for a clear disclosure, and is not to be construed as an exemplification of the prior art.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; it is obvious to those skilled in the art that a plurality of embodiments of the present invention may be combined. Such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present invention.

Claims

1. The utility model provides a partial discharge ultrasonic signal conditioning device suitable for multiple application scene which characterized in that: comprises an input frequency selection protection unit (1), a PGA unit (2), a program control frequency selection unit (3) and an acquisition driving unit (4) which are sequentially transmitted by signals;

the input frequency-selecting protection unit (1) comprises a high-pass RC filter with the characteristic of 10KHz and a low-capacitive protection circuit which can limit the amplitude of an input signal to be 0.3V higher than a positive power supply rail and 0.3V lower than a negative power supply rail; the input frequency-selecting protection unit (1) is electrically connected with the PGA unit (2);

the PGA unit (2) is provided with an amplifier LNA of which the input end is electrically connected with the output end of the input frequency selection protection unit (1) and an amplifier PGA of which the input end is electrically connected with the output end of the amplifier LNA;

the program control frequency selection unit (3) comprises an analog switch and a plurality of analog filtering frequency selection units;

the acquisition driving unit (4) comprises a frequency reduction amplifier and has the functions of 20dB gain amplification and frequency reduction.

2. The partial discharge ultrasonic signal conditioning device suitable for multiple application scenarios according to claim 1, wherein: the amplifier PGA comprises an amplifier and a program-controlled precise resistance network; the program-controlled precise resistance network comprises an analog switch with the on-resistance smaller than 1 omega and a plurality of high-stability precise resistors.

3. The partial discharge ultrasonic signal conditioning device suitable for multiple application scenarios according to claim 1, wherein: the input frequency-selecting protection unit (1) comprises diodes D1, D2, D3 and D4, capacitors C1 and C2, and resistors R1 and R2;

a pin 4 and a pin 5 of a chip U1 are directly connected to the output end of the differential high-pass RC filter respectively; the pin 15 is connected to pins 3, 14, 11 and 6 of the chip U2 through resistors R3, R4, R5 and R6 respectively; a pin 2 of the chip U1 is connected to a corresponding terminal pin of the chip U2;

the program-controlled frequency selection unit (3) comprises a chip U3, capacitors C4, C5, C6, C7, C8 and C9, and inductors L1, L2 and L3; the pin 11 of the chip U1 is connected with the corresponding pin of the chip U3 through a coupling capacitor C3;

the output pins 3, 14 and 11 of the chip U3 are respectively connected with the corresponding first, second and third filter circuits;

the acquisition driving unit (4) comprises a chip U4, resistors R7, R8 and R9, and capacitors C10 and C11;